Tech —

Xiaomi Mi Mix review—This is what the future of smartphones looks like

Xiaomi elegantly solves a lot of problems to create a more screen-centric smartphone.

The front-facing camera

Another oddity in this design is the front-facing camera. By definition it has to be on the front, but thanks to the bezel maximizing, it's in the bottom right corner. It reminds me of the Dell XPS 13, another device that displaced the camera to make room for a smaller bezel. In the normal orientation, both devices have terrible camera angles. But with a smartphone instead of a laptop, fixing this is a piece of cake—just flip it over. The recommended selfie mode is with the "bottom" bezel at the top, which results in a normal front-facing camera orientation. Whenever the camera is active, auto-rotate mode enables a 180-degree mode, so the whole UI flips over, too.

Old smartphone design makes the compromise of making the screen smaller and spending more space on a top camera. Alternatively, this solution enables a larger screen and less wasted space in exchange for having to flip the phone over when it's selfie or video call time. It's a different compromise than the one most people are used to, but I think this change is a net positive one. You use the screen way more than the camera, so it makes sense to prioritize the screen.

The screen

The Mi Mix has smaller top and bottom bezels, but with a similar body shape to other smartphones, that means the screen is taller than usual. The Mi Mix has a 17:9 aspect ratio with a "1080p" resolution of 2040×1080, but Xiaomi says the 17:9 aspect ratio works out to 16:9 after you subtract the on-screen navigation buttons it added to the phone.

There's another unique design touch when it comes to the display—the corners are rounded. Pushing the display all the way up to the top corners of the phone means chopping off a few inconsequential pixels. This looks amazing and doesn't really hurt anything in our eyes. Most of the time the corners are taken up by the status and navigation bars, and even when they aren't, you're only missing a few pixels.

With all the extra stuff out of the way, the screen can take up a massive amount of space on the front of the device. Xiaomi decided to go big—really big—for the Mi Mix: it's packing a 6.4-inch display. That size combined with a 1080p resolution doesn't match the insane pixel densities that ship on most Android phones, but the 500+ ppi displays are overkill anyway. The Mi Mix has 362 ppi—still more than an iPhone 7—and looks great.

A lot of people will probably have a problem with the size, since it is absolutely massive. Sure, thanks to the minimal bezels it's "only" the size of a Nexus 6, but the Nexus 6 was already a pocket buster. This is right on the border of something that's pocketable. While wide appeal probably isn't the goal for a "concept" device, a more "mainstream" size (say, a 5.5-inch "body," not necessarily screen size) would have been nicer.

The auto brightness sensor was moved around to make way for the screen, as well. It's now at the bottom of the phone right in the center of the chin. I haven't run into any problems with it there—sure, occasionally your hand passes over it, but the brightness adjustments happen gradually enough that that a temporary shadow doesn't affect it.

I've seen a lot of theories online about this design being prone to accidental touch input. The side bezels on the Mi Mix are just as small as the side bezels on other phones, so if you don't have trouble with every other smartphone, you shouldn't have trouble with this. There also seems to be a good amount of palm rejection—if you put a death grip on the phone and contact the screen, it tends to ignore any touch points that aren't fingertip shaped. The very top of the device, oddly, doesn't have any accidental touch rejection, so you do need to be a little careful when you're holding the phone in landscape. That's not hard to do, though.

Handle with care

The back has two modes: a freshly cleaned mirror finish and..

...a gross mess of fingerprints.

I've also seen some speculation online that the smaller bezels will somehow lead to a more fragile device. Like nearly every smartphone, the front of this device is edge-to-edge glass. If you drop it on the glass, you'll probably shatter it. None of that has anything to do with the location of the LCD, though.

What absolutely does make this more fragile than other phones is the all-ceramic body. The back, sides, corners, and buttons are all made out of a hard ceramic material. Xiaomi says the ceramic back is harder than glass, so it won't scratch in some circumstances when a glass-backed device would.

Of course, an all-glass phone isn't a great benchmark to hold yourself against—metal would have been much more durable. Most modern electronics aren't designed to be dropped, but I think the durability boost from metal (at the cost of more complicated radio engineering) is worth the tradeoff. The other major glass-back manufacturer is Samsung, but at least those phones have a metal frame. On the Mi Mix, even the sides and corners are ceramic. I'd imagine a single drop could make it shatter like a dinner plate.

In terms of feel, I couldn't tell the difference between Xiaomi's ceramic back and a glass one—they're both hard, smooth, glossy cold surfaces. The Mi Mix also loves to collect fingerprints. It feels fine, but I still prefer the stiff, metal back of the HTC 10 to this.

With such a minimal front bezel, the fingerprint reader is on the back of the device. This has been the standard location for LG and Google phones from the past couple of years, but on the Mi Mix using the rear fingerprint reader is much less convenient than on other phones. The downside to a rear fingerprint reader is that you always have to pick up the phone to unlock it. This is fine if you're pulling it out of a pocket, but it means you must pick up the phone to use it if it has been sitting on a desk.

Google and LG devices both get around this by supporting Google's "Smart Lock" features in Android. Rather than just being locked all the time, this lets the phone lock intelligently with a number of factors. You can tell the phone to stay unlocked at certain locations, like your home or office, or you can tell it to not lock if it's paired to a certain Bluetooth device. Both of these make it a lot easier to deal with the "on desk" use case.

Thanks to Xiaomi's heavy modification of Android, Smart Lock doesn't work on the Mi Mix. It makes using the rear fingerprint reader a huge pain in the butt, since most of the time I have my phone on my desk. When a notification comes in, I can immediately look at it, but on the Mi Mix I have to pick up the phone and unlock it. It's fine to use the rear fingerprint reader on a Google Phone to secure the lock screen, but on the Mi Mix it's just too much of a hassle at home.

Android 7.0 lets you change the UI scale, so you can actually see more on the 5.5-inch Pixel XL than on the 6.4-inch Mi Mix.

The notification panel works like every other Android phone now—pull down once for notifications, and again for more quick settings toggles.

The new design is nice, but we ran into the occasional white-on-white color issue.

The Recent Apps screen looks like iOS.

There's now a settings search!

In my Android 7.0 Nougat review, I said the OS allowed you to "do more on your gigantic smartphone" with features like split screen and an adjustable UI scale. As one of the biggest smartphone displays ever, the 6.4-inch Mi Mix seems like a natural fit for the more capable Android 7.0. But never mind—the Mi Mix only ships with Android 6.0. You won't be getting any of those great big-screen features on this big-screen phone.

Specifically, this is Android 6.0 Marshmallow with Xiaomi's "Miui 8" skin on top. Miui's development is rather unique for an Android skin—it's a UI that gets plastered on top of many different Android OS versions and devices. With Miui 8, Xiaomi is supporting devices all the way back to 2012's Xiaomi Mi 2, which still runs Android 5.0 Lollipop. And since the Miui 8 UI is designed to work across many Xiaomi devices, and the oldest ones run Android 5.0, the UI is limited to Android 5.0 features.

As you'd expect with the mish-mash of Android versions, a lot of things you might expect to work don't work. Direct share, a feature that populates the "share" dialog box with contacts in addition to apps, was removed. As we mentioned before, Google's Smart Lock doesn't work, which seriously damages the usefulness of the rear fingerprint reader. Multi-user support is dead, too.

It's really a shame the Mi Mix doesn't have Android 7.0's UI scaling feature. As a 6.4-inch phone, the default UI scale is huge. You don't get to see more of your favorite apps on the bigger screen, everything is just bigger. The UI is so big it looks like something designed for the vision impaired.

Xiaomi also messed with the way lock screen notifications work, making the lock screen much less useful. The lock screen only displays new notifications, where on normal Android the lock screen is a carbon copy of the notification panel. If the phone is off and notifications come in, they will display once on the lock screen, but in subsequent viewings, the lock screen will be blank.

As usual, Miui takes a lot from iOS, with an iPhone-style horizontal recent apps list and a home screen without an app drawer. I should mention that, as a China-only phone, the Mi Mix is loaded with Xiaomi's Chinese ROM. Even if you set it to "English," a lot of included apps aren't in English. There are also a lot of services that don't work, like Xiaomi's Mi Music and Mi Video.

Miui has improved a bit with version 8, though. The notification panel has been revamped to work more like a normal version of Android. Now when you pull down, you get the first few power toggles, and pulling down again expands the quick settings panel. Xiaomi has also seen fit to cram a weather report in here, along with a search box of some kind (it's in Chinese). There's also the addition of one or two Marshmallow features—Android 6.0's permission system is here and working, along with settings search.

This is Xiaomi's first phone with on-screen navigation buttons. For hardware buttons on devices like the Mi 5, the company used a hardware home button flanked by two unlabeled buttons, which took some getting used to. With on-screen buttons, you get labels and the ability to swap the button order, which is nice. Oddly the company still insists on making the Recent Apps button look like an old school menu. Sure, you can make the button double as a menu button, but no apps—including Xiaomi's—have app-wide menus anymore. With the switch to on-screen buttons, it would be nice to have the option for a more normal icon.

While the hardware is new and exciting, Miui 8 is a deal breaker. It's just a mess to deal with. Most third-party Android skins are functionally intact but have clunky "change for change's sake" designs that clash with the Google apps and the third-party ecosystem. Miui isn't just weird aesthetically; there are also a ton of missing features.

If Xiaomi really wants to be competitive with the high-end offerings in the smartphone market, it needs to revamp its software development and make a version of Miui exclusively for the newest version of Android with all the features intact. When you sign up for Android you get these features for free; breaking them is just inexcusable.

Ron Amadeo
Ron is the Reviews Editor at Ars Technica, where he specializes in Android OS and Google products. He is always on the hunt for a new gadget and loves to rip things apart to see how they work. Emailron@arstechnica.com//Twitter@RonAmadeo